Ranitidine [N-[2-[[[5-(dimethylamino)methyl-2-furanyl]methyl]thio]ethyl]-N′-methyl-2-nitro-1, 1-ethenediamine] and physiologically acceptable salts thereof (having, for example, the empirical formula C13H22N4O3S—HCl and the structural Formula I shown below) are disclosed in British Patent Specification No. 1565966.

According to current prescribing information, the compound of Formula I is indicated for short-term treatment of active duodenal ulcer (most patients found to heal within 4 weeks; studies available have not assessed the safety of ranitidine in uncomplicated duodenal ulcer for periods of more than 8 weeks); maintenance therapy for duodenal ulcer patients at reduced dosage after healing of acute ulcers (no placebo-controlled comparative studies have been carried out for periods of longer than 1 year); the treatment of pathological hypersecretory conditions (e.g., Zollinger-Ellison syndrome and systemic mastocytosis); short-term treatment of active, benign gastric ulcer (most patients found to heal within 6 weeks; the usefulness of further treatment has not been demonstrated; studies available have not assessed the safety of ranitidine in uncomplicated, benign gastric ulcer for periods of more than 6 weeks); maintenance therapy for gastric ulcer patients at reduced dosage after healing for acute ulcers (placebo-controlled studies have been carried out for 1 year); treatment of GERD (symptomatic relief found to commonly occurs within 24 hours after starting therapy with 150 mg b.i.d.); treatment of endoscopically diagnosed erosive esophagitis (symptomatic relief of heartburn found to commonly occur within 24 hours of therapy initiation with 150 mg b.i.d.); and maintenance of healing of erosive esophagitis (placebo-controlled trials have been carried out for 48 weeks).
Many of the formulations containing the compound of Formula I disclosed in British Patent Specification No. 1565966 are known to be unstable and, therefore, not appropriate for marketable formulations that are required to be stable. U.S. Pat. No. 4,585,790, on the other hand, discloses improved aqueous formulations of ranitidine that are more stable. That patent discloses ranitidine formulations having a pH in the range 6.5 to 7.5 that are suitable formulations for injections for intravenous and intramuscular administration, continuous infusions, and oral preparations such as syrups. Similarly, U.S. Pat. No. 5,068,249 discloses stabile, aqueous formulations of ranitidine containing ethanol as a stabilizer. That patent describes a pharmaceutical composition which is an aqueous formulation of ranitidine and/or one or more physiologically acceptable salts thereof containing ethanol and that is suitable for administration to patients and will, in general, contain at least one conventional pharmaceutical excipient in addition to the ethanol and ranitidine and/or physiologically acceptable salts thereof.
U.S. Pat. No. 6,265,449 discloses an aqueous pharmaceutical composition for oral administration comprising ranitidine, or a pharmaceutically acceptable salt thereof, that contains alcohol and low color, metal, turbidity (LCMT) sucrose, which was found to improved stability, bioavailability and taste-masking of ranitidine while allowing the volume of the alcohol required in the solution to be reduced.
A commercially available version of a stable pharmaceutically acceptable salt form of the compound of Formula I is known as ZANTAC® syrup, which is described in prescribing information as being a clear peppermint-flavored liquid that contains 16.8 mg of ranitidine-HCl equivalent to 15 milligrams (mg) of ranitidine per 1 milliliter (ml) (75 mg/5 mL) in bottles of 16 fluid ounces (one pint). Because of its relative instability, ZANTAC® is usually stored between about 4° and about 25° C. (39° and 77° F.) in tight, light-resistant containers.